• Title, Summary, Keyword: Engine Noise

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Speech Enhancement Based on Feature Compensation for Independently Applying to Different Types of Speech Recognition Systems (이기종 음성 인식 시스템에 독립적으로 적용 가능한 특징 보상 기반의 음성 향상 기법)

  • Kim, Wooil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.10
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    • pp.2367-2374
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    • 2014
  • This paper proposes a speech enhancement method which can be independently applied to different types of speech recognition systems. Feature compensation methods are well known to be effective as a front-end algorithm for robust speech recognition in noisy environments. The feature types and speech model employed by the feature compensation methods should be matched with ones of the speech recognition system for their effectiveness. However, they cannot be successfully employed by the speech recognition with "unknown" specification, such as a commercialized speech recognition engine. In this paper, a speech enhancement method is proposed, which is based on the PCGMM-based feature compensation method. The experimental results show that the proposed method significantly outperforms the conventional front-end algorithms for unknown speech recognition over various background noise conditions.

A Study of the Manufacturing Process and Physical Properties of Needle Punched PET Nonwovens for an Air Intake Duct (에어 덕트용 PET 니들펀칭 부직포의 제조 및 물성에 관한 연구)

  • Bae, Younghwan;Doh, Song Jun
    • Textile Science and Engineering
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    • v.49 no.4
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    • pp.263-269
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    • 2012
  • An air intake duct is an automotive part for transferring outside air to the internal combustion engine where the air and fuel are mixed and consumed. While this part has been primarily made of engineering plastics, many manufacturers are attempting to apply textile nonwovens due to their superior sound absorbing performance and lightweight characteristics. In this paper, we studied the manufacturing process of needle punched nonwoven fabric and analyzed various properties in order to investigate the applicability of textile nonwoven as a material for automobile air intake ducts. The nonwoven web was prepared by opening, mixing and carding PET staple fibers and binder fibers. The web was physically bonded by the needle punching process. In addition, we applied heated air through the nonwoven web to improve the mechanical properties of the needle punched nonwoven fabrics by the thermal bonding of interlocking constituent fibers. The results of the tensile test of the nonwoven demonstrated that the hot air treatment to the needle punched nonwoven decreased the elongation of nonwoven, which significantly affects the processability of the air duct production process. Also, the porous structure of the nonwoven improved the sound absorbtion property compared to normal PP plastic. Therefore, the air intake duct made of PET needle punched nonwoven could contribute to decreasing the noise level inside automobiles.

Development of Voice Information System for Safe Navigation in Marine Simulator (시뮬레이터 기반 음성을 이용한 항행정보 안내시스템의 개발)

  • Son N. S.;Kim S. Y.
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.5 no.3
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    • pp.28-34
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    • 2002
  • As the technology of Speech Recognition(SR) and Text-To-Speech(TTS) develops rapidly, voice control and guidance system is thought to be very helpful for safe navigation. But Voice Control and Guidance System(VCGS) is not yet so popularly included in Navigation Supporting System(NSS). The main reason of this is that VCGS is so complicated and user-unfriendly that navigation officers hesitate to use VCGS. Frequent errors in operating VCGS due to low rate of SR are another reason. To make VCGS more practicable for safe navigation, we design the user-friendly VCGS. Firstly, by using interviews we survey functions and procedures that navigation officers want to be included in VCGS. Secondly, to raise the rate of SR, we tun the environmental noise in bridge and to reduce the errors due to low rate of SR in operating VCGS, we design the functions of self-correction. Also we apply a user-independent SR engine so that procedures of teaming of speakers is basically not necessary. Using simulator experiments the functions and procedures of the user-friendly YCGS for safe navigation are evaluated and the results of evaluation are fed back to the design. As a result, we can design the VCGS more helpful for safe navigation. In this paper, we describe the features of the user-friendly VCGS for safe navigation and discuss the results of simulator experiments.

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Study on the shaping process of turbocharger nozzle slide joint (터보차저 노즐 슬라이드 조인트의 정형공정에 관한 연구)

  • Kim, Bong-Ju;Lee, Seon-Bong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.1
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    • pp.107-114
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    • 2017
  • A turbocharger is an engine supercharger that is driven by exhaust gas. It improves the output and fuel efficiency by increasing the charging efficiency of the mixture gas, which is achieved by changing the rotatory power of the turbine connected to the exhaust passage. It is important to control the supercharging for this purpose. A nozzle slide joint is one of the core parts. Austenitic stainless steel is currently used as the material for this part, and its excellent mechanical properties include high heat resistance and corrosion resistance. However, because of its poor machinability, there are many difficulties in producing products with complicated shapes. Machining is used in the production of nozzle slide joints for high dimensional accuracy after metal powder injection molding. As design variables in this study, we investigated the sintering temperature, product stress, deformation rate, radius of curvature of the punch, and angle of the chamfer punch, which are related to the strain and shapes. The goal is to suggest a forming process using Nitronic 60 that does not require machining to manufacture a nozzle slide joint for a turbocharger. Accordingly, we determined the best process environment using finite-element analysis, the signal-noise ratio, and the Taguchi method for experiment design. The relative density and hydrostatic pressure of the final product were in accordance with the results of the finite element analysis. Therefore, we conclude that the Taguchi method can be applied to the design process of metal powder injection molding.

Research on Vehicle Diagnostic and Monitoring technology Using WiBro Portable Device (와이브로 휴대기기를 사용한 차량진단 및 모니터링 기술에 관한 연구)

  • Ryoo, Hee-Soo;Won, Yong-Gwan;Park, Kwon-Chul;Ahn, Yong-Beom
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.10
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    • pp.17-26
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    • 2010
  • This is concerned with the technology to monitor the vehicle operation, failure and disorder by using WiBro portable device. More precisely, the technology makes it possible that the information collection device is connected to both ECU(Electronic Control Unit) which is the device for controlling engine, transmission, brake, air-bag, etc that are connected to in-vehicle network and OBD-II connector that is for data collection from various sensors. In addition, with a WiBro portable device (cell phone, PDA, PMP, UMPC, etc). equipped with a vehicle diagnostic programs, information for operation, failure and malfunction can be obtained and analyzed in real-time, and alarm is alerted when the vehicle is in abnormal status, which makes the early reactions to the status. Furthermore, the collected data can be sent through WiBro network to the server managed by the company specialized in managing the vehicles, thus the technology could help the drivers who have less knowledge about their auto-vehicles have safe and economic driving. There is always a possibility of malfunction due to various types of noise that are caused by wring-harness when the device is wired-connected. In this research, in order to overcome this problem, we propose a system configuration that can do monitoring and diagnosis with a device for collecting data from vehicle and a personal WiBro device. Also, we performed research on data acquisition and interlock for the system defined by the definition for information and data sharing platform.

Design of Sliding Mode Fuzzy Controller for Vibration Reduction of Large Structures (대형구조물의 진동 감소를 위한 슬라이딩 모드 퍼지 제어기의 설계)

  • 윤정방;김상범
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.3
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    • pp.63-74
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    • 1999
  • A sliding mode fuzzy control (SMFC) algorithm is presented for vibration of large structures. Rule-base of the fuzzy inference engine is constructed based on the sliding mode control, which is one of the nonlinear control algorithms. Fuzziness of the controller makes the control system robust against the uncertainties in the system parameters and the input excitation. Non-linearity of the control rule makes the controller more effective than linear controllers. Design procedure based on the present fuzzy control is more convenient than those of the conventional algorithms based on complex mathematical analysis, such as linear quadratic regulator and sliding mode control(SMC). Robustness of presented controller is illustrated by examining the loop transfer function. For verification of the present algorithm, a numerical study is carried out on the benchmark problem initiated by the ASCE Committee on Structural Control. To achieve a high level of realism, various aspects are considered such as actuator-structure interaction, modeling error, sensor noise, actuator time delay, precision of the A/D and D/A converters, magnitude of control force, and order of control model. Performance of the SMFC is examined in comparison with those of other control algorithms such as $H_{mixed 2/{\infty}}$ optimal polynomial control, neural networks control, and SMC, which were reported by other researchers. The results indicate that the present SMFC is an efficient and attractive control method, since the vibration responses of the structure can be reduced very effectively and the design procedure is simple and convenient.

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Feature Extraction Algorithm for Distant Unmmaned Aerial Vehicle Detection (원거리 무인기 신호 식별을 위한 특징추출 알고리즘)

  • Kim, Juho;Lee, Kibae;Bae, Jinho;Lee, Chong Hyun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.3
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    • pp.114-123
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    • 2016
  • The effective feature extraction method for unmanned aerial vehicle (UAV) detection is proposed and verified in this paper. The UAV engine sound is harmonic complex tone whose frequency ratio is integer and its variation is continuous in time. Using these characteristic, we propose the feature vector composed of a mean and standard deviation of difference value between fundamental frequency with 1st overtone as well as mean variation of their frequency. It was revealed by simulation that the suggested feature vector has excellent discrimination in target signal identification from various interfering signals including frequency variation with time. By comparing Fisher scores, three features based on frequency show outstanding discrimination of measured UAV signals with low signal to noise ratio (SNR). Detection performance with simulated interference signal is compared by MFCC by using ELM classifier and the suggested feature vector shows 37.6% of performance improvement As the SNR increases with time, the proposed feature can detect the target signal ahead of MFCC that needs 4.5 dB higher signal power to detect the target.

Comparison of Control Strategies for Military Series-Type HEVs in Terms of Fuel Economy Based on Vehicle Simulation (시뮬레이션을 이용한 군용 직렬형 HEV 의 주행 전략에 따른 연비 성능 비교에 관한 연구)

  • Jung, Dae-Bong;Kim, Hyung-Jun;Kang, Hyung-Mook;Park, Jae-Man;Min, Kyoung-Doug;Seo, Jung-Il
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.1
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    • pp.31-36
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    • 2012
  • Military vehicles, compared to conventional vehicles, require higher driving performance, quieter operation, and longer driving distances with minimal fuel supplies. The series hybrid electric vehicle can be driven with no noise and has high initial startup performance, because it uses only a traction motor that has a high startup torque to drive the vehicle. Moreover, the fuel economy can be improved if the vehicle is hybridized. In series hybrid electric vehicles, the electric generation system, which consists of an engine and a generator, supplies electric energy to a battery or traction motor depending on the vehicle driving state and battery state of charge (SOC). The control strategy determines the operation of the generation system. Thus, the fuel economy of the series hybrid electric vehicle relies on the control strategy. In this study, thermostat, power-follower, and combined strategies were compared, and a 37% improvement in the fuel economy was implemented using the combined control strategy suggested in this study.

Recent Progress in Air Conditioning and Refrigeration Research - A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2004 and 2005 - (공기조화, 냉동 분야의 최근 연구 동향 -2004년 및 2005년 학회지 논문에 대한 종합적 고찰-)

  • Choi, Yong-Don;Kang, Yong-Tae;Kim, Nae-Hyun;Kim, Man-Hoe;Park, Kyoung-Kuhn;Park, Byung-Yoon;Park, Jin-Chul;Hong, Hi-Ki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.1
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    • pp.94-131
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    • 2007
  • A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.